Sparta conquered fertile lands to the west and made its inhabitants serfs whose labors supported the Spartan state and a fully professional army. Spartan citizens were forbidden any non military profession. The army also protected Sparta against rebellions.
From Wikipedia
The helots (in Classical Greek ??????? / Heílôtes) were the serfs of Sparta. They should not be confused with the chattel slaves, who were much less common (or nonexistent) in Sparta.
Helots were assigned to citizens to carry out domestic work or work on their klêroi. Mention is made in various sources of these servants accompanying this or that Spartan. Plutarch (Life of Agesilaus, III, 1) has Timaia, the wife of King Agis II, "being herself forward enough to whisper among her helot maid-servants" that the child she was expecting had been fathered by Alcibiades, and not her husband, indicating a certain level of trust. According to some authors, in the fourth century BC, citizens also used chattel-slaves for domestic purposes. However, this is disputed by others. Some helots were also servants to young Spartans during their agoge, the Spartan education; these were the ??????? / móth?nes (see below). Finally, helots, like slaves, could be artisans or tradesmen.
They were required to hand over a predetermined portion of their harvest (??????? / apophorá), with the helot keeping the surplus. According to Plutarch, this portion was 70 medimnoi of barley for a man, 12 for a woman, as well as a quantity of oil and wine corresponding to an amount reasonable for the needs of a warrior and his family or a widow respectively. The existence of the apophorá is contested by Tyrtaeus, cited by Pausanias; "Secondly, though no fixed tribute was imposed on them, they used to bring the half of all the produce of their fields to Sparta.... Like asses worn by their great burdens, bringing of dire necessity to their masters the half of all the fruits the corn-land bears." (IV, 14, 4–5). Pausanias is describing the period immediately after the first Messenian War, when conditions were no doubt more severe.
Having paid their tribute, the helots could often live quite well; the lands of Laconia and Messenia were very fertile, and often permitted two crops per year. A certain amount of wealth was achievable: in 223 BC, 6,000 helots purchased their freedom for 500 drachmas each, a considerable sum at the time. Nevertheless, Spartans did take measures to keep the helots from getting too rich.
